• Jiandang Zhang, Zheng Wang, Pengfei Chi, and Cheng Chi.
• Department of spine surgery, The Chinese PLA General Hospital, Beijing, China.
• Spine. 2021 Mar 15; 46 (6): 366-373.

Study DesignRetrospective case-control radiographic study.ObjectiveThe aim of this study was to explore whether directionality of lumbosacral fractional curve relative to C7 plumb line (PL) affected postoperative coronal imbalance in patients with degenerative lumbar scoliosis (DLS).Summary Of Background DataThe spatial relationship between lumbar main curve and C7 PL was reported to have impact on postoperative coronal imbalance in DLS. Although fractional curve played more important role than lumbar main curve in DLS, the spatial relationship between fractional curve and C7 PL and their impact on the postoperative coronal balance are still unknown.MethodsOne hundred one DLS patients treated with posterior instrumented fusion were reviewed. Coronal measurements included C7 migration, fractional curve, L4/L5 coronal tilt, major Cobb angle. Based on directionality of fractional curve (orientation of L4 coronal tilt was used to represent it) relative to C7 PL preoperatively, coronal patterns was separated into: consistency pattern, L4 coronally tilts toward C7 PL; opposition pattern, L4 coronally tilts opposite C7 PL; the distributions of these two patterns and Type A, B,C were analyzed. According to postoperative C7 migration, patients were divided into imbalanced group and balanced group.ResultsCompared to balanced group, the imbalanced group had higher percentage of preoperative consistency pattern (80.6% vs. 33.8%, P < 0.001) and Type C (36.1% vs. 7.7%, P < 0.001); larger fractional curve or L4 coronal tilt pre- and postoperatively, larger L5 coronal tilt postoperatively. Logistic regression analysis showed predictors for postoperative coronal imbalance were consistency pattern (odds ratio [OR] 5.103, 95% confidence interval [CI]: 1.660-15.687, P = 0.004) and type C (OR 4.061; 95% CI: 1.056-15.618; P = 0.041).ConclusionDirectionality of fractional curve relative to C7 PL was associated with postoperative coronal imbalance in DLS patients. In addition to type C, consistency pattern might be an independent risk factor for postoperative coronal imbalance.Level of Evidence: 3.Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.

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